The call was later deemed a hoax, but students described a scene of confusion, with many saying the university failed to provide prompt information about the threat and instructions for evacuation.

A Cal State L.A. student runs past a sign taped on a law enforcement vehicle… (Don Bartletti / Los Angeles…)

The caller stood at a pay phone outside a Carl's Jr. in El Monte and warned police: Bombs will explode in two hours, he said. One at Cal State L.A. , the other at UC Berkeley.

The reactions of the two public universities, though, were markedly different.

At Cal State L.A., administrators sounded fire alarms across campus, evacuated dorm rooms and classrooms and canceled school for the rest of the day. UC Berkeley police officials deemed the same threat "low credibility" and the campus proceeded with business as usual.

The threat was later determined to be false, but students and faculty at Cal State L.A. described a scene of chaos and confusion.

"I'm assuming it's a hoax," student Jonny Barrios said during the ordeal, "but by the way they're taking it — especially after Boston — they should have better communication of telling students what's going on instead of 'Get out, get out, get out!' "

University spokesman Paul Browning said Cal State L.A. sent a message through its opt-in emergency-alert system and posted notices on Facebook and Twitter telling students to evacuate.

But students and faculty members said they felt the university failed to provide prompt information about the threat and instructions for evacuation.

Barrios tweeted his frustration: "I am still waiting to receive either a text message or an email!!! And this happened about 1 hour and 30 mins ago."

Student Alexander Salas, 22, said he got an automated call soon after the alarm went off telling him to evacuate, but little else.

"This time they didn't give us information," he said. "They didn't tell us what was going on."

Several students who said they had signed up for alerts never received them.

Senior Nicolle Fedor said she was taking a quiz when the alarm in her building went off. Students waited outside the building for about 15 minutes before a motorcycle officer said they had to go home.

Traffic getting off campus was jammed, she said, with an inadequate number of officers to handle the crowd.

"If there was really a bomb, everybody on campus would have been gone in an hour," she said.

Even though Fedor had not signed up for the campus alerts, she said the school "at the very least" could have notified her through the university email system.

Browning acknowledged not all students are signed up for the opt-in emergency-alert system, but could not say whether school officials thought to send email notifications to university-affiliated accounts.

He said the threat was credible enough to order an evacuation.

"We don't think it was an overreaction at all," Browning said. "We have to take something like that seriously, especially when another police agency — El Monte — calls and says there was a threat made. We want to let the campus community know their safety is the most important thing, especially after an incident like that in Boston."

Thursday's bomb threat was the latest in a number of similar calls in Los Angeles since Monday's attack at the Boston Marathon. On Wednesday, a briefcase in a UCLA parking structure prompted authorities to briefly shut down the structure and some building exits. In Silver Lake later that day, police evacuated a strip mall after someone left a pressure cooker-like device in the parking lot.

LAPD Lt. Andy Neiman said an uptick in bomb calls and reporting of suspicious packages is not uncommon after a national event and for a city as large as Los Angeles.

"There's a natural tendency for the public to be more acutely aware of their surroundings following tragic incidents that occur in the public spectrum," Neiman said. "As a result, following Boston we have seen a slight increase in the number of suspicious or unattended package calls throughout the city."